Thermochromic coating and method of manufacturing thereof

ABSTRACT

A thermochromic coating that comprises a thermo chromic compound and a polyurea resin. The thermo chromic compound and polyurea resin form a thermochromic layer. The coating optionally has a protective layer containing a resin and a UV-blocking material arranged on top of the thermochromic layer. A reflective layer containing a reflective material is optionally arranged between the thermo chromic layer and the substrate. A thermochromic coating is formed by applying successive reflective, thermochromic, and protective layers on a substrate.

CROSS REFERENCE TO PRIORITY APPLICATION

This application is based upon and claims the benefit of priority fromU.S. patent application Ser. No. 12/953,794, filed on Nov. 24, 2010,which claims the benefit of priority from Provisional U.S. PatentApplication 61/264,103 filed on Nov. 24, 2009, the entire contents ofwhich are incorporated by reference herein.

BACKGROUND

1) Field of Disclosure

The present disclosure is related to the field of building materials.This disclosure has particular applicability to coatings for buildingmaterials having thermo chromic properties.

2) Description of Related Art

Mankind has always sought methods to improve his living conditions. Thedevelopment of protective shelters provided needed safety from harshenvironments. Cooling and heating systems powered by fossil fuelsgreatly increased the comfort of these shelters. However, there is adesire to reduce the amount of energy expended for cooling and heatingfor a multitude of reasons. For example, reasons include lowering thefinancial cost to the building owner and reducing the environmentalimpact from the use of fossil fuels. These reasons provide motivation todevelop non-energy using means to mediate the environment of interiors.

One way of reducing the amount of energy necessary to heat and cool astructure is to alter the color of the structure's exterior. As is wellknown, light colors, such as white, reflect sunlight, which in tumreduces the degree to which sunlight heats up a light-colored surface.Conversely, darker colors absorb sunlight, which cause a dark surface toheat up under exposure to sunlight. Previously, however, application ofthis principle to buildings and other structures has not been deemed areasonable solution, as the cost and effort necessary to periodicallyalter the color of structures, such as by painting or covering, wasprohibitive.

Thermochromic compositions change color in response to temperaturefluctuations. Conventional reversible thermochromic compositions exhibitreversible thermochromic properties such that they begin to becomecolor-extinguished in the course of temperature rise caused in acolor-developed state, present a completely color-extinguished state ata specific temperature or above, and begin to develop a color in thecourse of subsequent temperature drop and return to the color-developedstate.

The thermal or “UVI” radiation range is the range of frequencies in theUltraviolet, Visible and Infrared ranges which produce heat in objects,and which absorb those frequencies. The relative transparency/opacity ofa thermochromic material is dynamic with respect to the triggertemperature or trigger temperature range of the specific thermo chromicmaterial. For example, a thermochromic material having a triggertemperature of precisely 72 degrees Fahrenheit would be opaque to lightand thus would absorb thermal radiation in the UVI range at temperaturesbelow 72 degrees Fahrenheit and transparent, or non-absorptive, to UVIlight at temperatures above 72 degrees Fahrenheit.

Another desired property of shelters is to provide long term protectionwithout the need for extensive repair. Rain, heat and wind cause damageto exterior surfaces and as such, a means to prevent the deteriorationof these surfaces is an ever present goal in the field of structuredesign. One form of protection is the use of polyurethane coatings toprotect exposed surfaces from harmful elements. For example, U.S. Pat.No. 4,710,560 is directed toward a hydrophobic, crosslinked polyurethanefor use as a corrosion inhibiting coating on exposure to moisture atatmospheric conditions.

However, although the coating of a polyurethane resin can show variouskinds of properties depending upon the composition thereof, an importantdefect of the polyurethane resin is the discoloration and thedeterioration such as hydrolysis, when exposed to the outdoors over along period of time. Therefore, polyurethane resin coatings can beunsuitable for uses in which good durability is required.

It is also known that thermochromic materials can be added tothermoplastics, polyvinyl chloride (PVC) or other resins and molded intoany shape or design or made into sheets. The use of thermochromicmaterials in the coatings of structures has been explored. For example,Khaldi (U.S. Pat. No. 6,500,555) discloses thermochromic laminates,which predictably vary their ability to absorb or reflectelectromagnetic radiation. However, without the proper medium for whichthe thermo chrome is carried, the thermochrome and the coating arequickly deteriorated upon exposure to the elements.

Smith also teaches, in US Application 2008/0209825, a color changingsystem for structures that uses polyurethane laminates in a layeredstructure. However, as indicated above, problems occur with the use ofpolyurethanes alone.

SUMMARY

In order to overcome the problems discussed above, the presentdisclosure is directed to a thermochromic coating which comprises athermochromic compound and a polyurea resin, wherein the thermochromiccompound and polyurea resin form a thermochromic layer. The coatingoptionally comprises a protective layer containing a resin and aUV-blocking material, and the protective layer is arranged on top of thethermochromic layer. Optionally, a reflective layer containing areflective material is arranged between the thermochromic layer and thesubstrate.

The present disclosure is also directed toward a method for forming athermo chromic coating on a substrate comprising the step of forming athermochromic layer on the substrate, wherein the thermochromic layercomprises a thermochromic compound and a polyurea resin.

In another embodiment, the thermochromic coating also contains aprotective layer and reflective layer also formed of a resin. In certainembodiments, the protective and reflective layers use polyurea as theresin. Optionally, other resins may also be used, such as polyurethane,epoxy, acrylic, fluoropolymers, silicones, polyvinylidenefluoride(PVDF), polyvinyl chloride (PVC), rubbers including but not limited toepdm, and thermoplastic polyolefins (tpo).

In another embodiment of the present disclosure, the thermochromic layerfurther comprises a UV-blocking material. Optionally, a thermochromiccoating comprises one layer containing a thermo chromic compound, aUV-blocking material, and a resin. The thermochromic compound and theUV-blocking material are interspersed within the resin material.

Additional advantages and other features of the present disclosure willbe set forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from the practice of thedisclosure. The advantages of the disclosure may be realized andobtained as particularly pointed out in the appended claims.

As will be realized, the present disclosure is capable of other anddifferent embodiments, and its several details are capable ofmodifications in various obvious respects, all without departing fromthe disclosure. Accordingly, the figures and description are to beregarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE FIGURES

The figures depict one or more implementations in accordance with thepresent teachings by way of example, not by way of limitation. In thefigures, like reference numerals refer to the same or similar elements.

FIG. 1 is a side view of a thermochromic coating according to oneembodiment of the present disclosure;

FIG. 2 is a side view of a thermochromic coating according to anotherembodiment of the present disclosure;

FIG. 3 is a side view of a thermochromic coating according to anotherembodiment of the present disclosure; and

FIG. 4 is a side view of a thermochromic coating according to anotherembodiment of the present disclosure.

DETAILED DESCRIPTION

The thermochromic coatings and methods for manufacturing the coatings ofthe present disclosure employ a coating or a multilayer structure thatchanges color in response to heating by sunlight or other thermal orradiation source. The coating changes from a certain color to white uponincreasing temperature. The change in color to white will then reducethe absorption of IR radiation and thereby significantly reduce theheating of the roof structure.

In one embodiment shown in FIG. 1, a thermochromic layer 10 is depositedon a substrate 100 such as EPDM rubber or the like and installed muchthe same way conventional roll roofing is installed. The thermochromiclayer 10 contains one or more thermochromic molecules, a UV resistantprotective compound and a polyurea resin to form a thermochromiccoating. One example of the polyurea carrier resin is an aliphaticpolyurea.

Polyureas are the reaction product of an isocyanate or polyisocyanatecomposition and an amine or polyamine composition. By careful selectionof the isocyanate component, in conjunction with selection of the aminecomponent, highly beneficial properties of a novel polyurea coatingmaterial are obtained. The selection of these ingredients, together withselection of optional alcohol or polyol components, results in a highlydurable coating that has low porosity, high elongation, and highhardness. Additionally, the selection of these components provides anenvironmentally friendly composition because it generates substantiallyno volatile organic compounds (VOCs). The ease and lower cost ingeneration of coatings according to the present invention providessubstantial manufacturing benefit and environmental benefit to both themanufacturer and the public at large.

The thermochromic coating composition of the present inventionsurprisingly may be applied with excellent aesthetic results in anextremely easy manner. Because of the selection of the ingredients, thecomposition may be sprayed or applied onto a surface or used in theformation of a composite, resulting in a high density and hard surfacepreviously only achievable through a lamination process utilizing heatand pressure. Thus, thin hard films may be easily prepared in anenvironmentally friendly manner.

Optionally, the thermochromic coating is comprised of a two layerstructure. For example, as is shown in FIG. 2, a thermochromic colorchanging layer 10 is first deposited on a substrate 100. A protectivelayer 20 is applied over the color changing layer 10. This protectivecoating 20 provides protection from weather and UV degradation. Thethermochromic molecules available today are generally unstable to longterm exposure to UV radiation in sunlight. Therefore the protectivelayer 20 is either applied as a separate layer or added to the singlecomponent structure. The protective layer 20 should be substantiallyclear as to allow for the thermochromic coating to be visible throughthe protective layer.

In another embodiment such as that shown in FI G. 3, a three layerstructure forms the thermochromic coating. The thermochromic coating isstructured such that a reflective layer 30 is deposited on a substrate100. In some embodiments, a thermochromic color changing layer 10 isapplied over the reflective layer 30. Then, a protective layer 20 isapplied over the thermochromic layer 10. The protective layer 20 may beused for weather protection and UV protection. Polyurea resins compriseat least one of the layers for this structure. Polyureas provideexcellent outdoor exposure properties for applications like roofing andothers.

In some embodiments, the resin further comprises a dendrimer orhyperbranched compound covalently bonded to the polyurea. Dendrimers andhyper-branched molecules are generally described as macromolecules,which are characterized by highly branched 3D structures that provide ahigh degree of surface functionality and versatility. Dendrimers aresynthesized from a molecule containing a central atom, such as nitrogen,to which carbon and other elements are covalently bound by a repeatingseries of chemical reactions that produce a spherical branchingstructure. As the process repeats, successive layers are added, and thesphere can be expanded to the desired size. One result of the repeatingchemical syntheses is a spherical macromolecular structure.Hyper-branched molecules do not generally have a structure as defined asdendrimers. However, hyper-branched molecules contain multiple branchesmuch like dendrimers.

Dendrimers and other highly branched polymeric structures having amineend-groups are termed “amino-terminated”. These end groups may beutilized in the reactions to form polyureas which result in highlybranched polymers of high molecular weight. The high branching addsstrength and high thermal stability to the polyurea.

Other resins capable of being utilized as resin materials for use in thelayers such as the reflective layers 30 and/or protective layers 20 inthe present disclosure include polyurethane, epoxy, acrylic, polyvinylalcohol, polyvinyl acetate, polyvinyl chloride, polyester, polyimide,polyether ether ketone, and polycarbonate.

The protective layer 20 uses nano-scale particles of titanium dioxide,iron oxide or other UV blocking inorganic material. Alternatively, thesenano-scale particles may be used in combination with well-establishedorganic UV blockers such as Tinuvins™ (Ciba) to yield very strong UVprotection while allowing full transmittance of the visible/IRwavelengths that lead to heating. The importance of nano-scale particlesis that when particle size is controlled to be below a given wavelengthof light, the particle can no longer absorb or block that wavelength.For optimum use of the thermochromic properties of the coating, it isdesirable to block all light exhibiting a wavelength below about 400 nm(block UV) and let all light exhibiting a wavelength above 400 nm(visible/IR) to pass through. As such, in certain embodiments of thepresent disclosure, the UV-blocking material comprises particles havinga diameter of from 0.005 μm to 0.4 μm. In other embodiments, theparticles have a diameter of from 0.01 μm to 2.5 μm.

The concentration of the UV-blocking particles should be sufficient toprovided adequate long term protection of the thermochromic molecules inthe thermochromic coating. Generally, the more UV-absorbing particlespresent in the coating, the greater the protection. However, too high ofconcentration of the UV-absorbing particles would cause problems insolubility of the particles, and added cost of components of thecoating. In some embodiments, the concentration of particles in theresin layer is from 0.1 wt % to 50 wt % of the total weight of thelayer. In other embodiments, the concentration of particles in the resinlayer is from 0.1 wt % to 15 wt % of the total weight of the layer. Inyet other embodiments, the concentration is from 0.5% to 1.0% of thetotal weight of the layer.

UV-blocking particles are comprised of titanium oxide or iron oxide.However, any UV-blocking material suitable for use with the materialsdisclosed herein is acceptable.

In some embodiments of the present disclosure, the thermochromiccompound is at least one selected from liquid crystals, cholestericliquid crystals, microencapsulated liquid crystals, leuco dyes,microencapsulated leuco dyes, spirolactones, spiropyrans, fluorans,cholesteryl nonanoates, cyanobiphenyls and inorganic pigments. However,the present disclosure is applicable to any suitable thermochromiccompound that can be formulated in a polyurea resin and have atransition temperature within the ranges needed for outdoor use.

In some embodiments, the present disclosure uses thermochromic materialsthat have a transition temperature of from about 5° C. to about 90° C.More specific temperature ranges for transition temperatures ofthermochromic materials of the present disclosure are from about 15° C.to about 30° C. In some embodiments, the transition temperature of thethermochromic material is 27° C.

According to the present disclosure, the method for forming athermochromic coating on a substrate comprises a step of applying athermochromic layer 10 on the substrate 100. The thermo chromic layer 10is made of a thermochromic compound and a polyurea resin. In otherembodiments, the method further comprises a step of forming a protectivelayer 20 on the thermochromic layer 10, the protective layer 20 having aUV-blocking material in a resin. According to one embodiment, the resinis a polyurea resin. However, other resins, such as polyurethane, epoxy,acrylic polyvinyl alcohol, polyvinyl acetate, polyvinyl chloride,polyester, polyimide, polyether ether ketone, and polycarbonate may beused in the protective layer.

In another embodiment of the present disclosure, the protective layer 20is adhered to the thermochromic layer 10 by use of an adhesive. Anysuitable adhesive that can withstand exposure to outdoor elements may beused.

In other embodiments, the method for forming a thermochromic coatingfurther comprises a step of, before forming the thermochromic layer 10,forming a reflective layer 30 on the substrate 100 such that thereflective layer 30 is located between the substrate 100 and the thermochromic layer 10.

In some embodiments, the substrate 100 is a carrier film, a scrimstructural sheet, a cellulosic carrier sheet, a non-woven carrier sheet,ethylene-propylene diene rubber, chlorosulfonated polyethylene rubber,asphalt shingles, a roof, a pipeline, a delivery pipe, a chemicalreactor, an industrial structure and a residential structure. However,applications of the present disclosure are not limited by theseexamples. It is the Applicants' intention that the thermochromiccoatings may be applied to any surface.

In another embodiment of the present disclosure, a method in whichadditional layers of thermochromes are added in order to reload orrecharge a coating, but not replace the entire roof coating structure,is provided. The method involves, in addition to any of the stepsmentioned previously, forming an additional layer 40 on the substrate,wherein the additional layer 40 comprises a thermochromic compound and apolyurea resin. A representative structure of such a thermochromiccoating is shown in FIG. 4. This method optionally includes amaintenance activity comprising a wash down of the roof structure, an“opening” of channels in the coating via a solvent wash (hopefullyacetone or t-Bac or the like, delisted no-VOC solvents) and simplebrushing or rolling of the surface with thermochromic compounds. Assuch, another embodiment of the present disclosure is adding a further astep of forming an additional layer 40 on the substrate, wherein theadditional layer 40 comprises a thermochromic compound and a polyurearesin.

Optionally, another embodiment is a method to coat very thin layers ofthermochromic materials on peelable sheets that could be removedperiodically.

As thermochromic molecules are susceptible to degradation anddecomposition during use with high temperature/high pressure impingementspray equipment which is common in the polyurea/polyurethane industry,applying these coated layers by low pressure cold spray orbrush/roll/squeegee is desirable.

The ability to deposit any of the structures in a factory environment togenerate rolls of finished goods that would be then shipped to jobsitesand applied by roofing contractors is desirable. This is particularlyimportant when polyureas are used as layer materials. The processincludes casting polyurea resin layers onto a release sheet orstructural receiver from a typical slot die coating head and then ovencuring the web in line. At a rewind station the polyurea will bestripped, if a release sheet is used, and rolled up on a spool to yieldwide webs of roofing material for use. In addition, the reactivechemistry we will be depositing will require very good process controland in-line mixing capabilities that narrow the number of machines thatwill be capable of producing this material. These roll goods areconverted (slit and/or chopped for example) into tiles, shingles,sheets, etc. for use in the field.

Another embodiment of the present disclosure is a method of multilayerslot die coating. This coating method allows the deposition of a singlelayer that contains a multilayer internal structure. This structureprovides for an internal structure with the UV protection at a topsurface, a thermochrome in the middle and a highly reflective layer atthe bottom, in one application.

The present disclosure can be practiced by employing conventionalmaterials, methodology and equipment. Accordingly, the details of suchmaterials, equipment and methodology are not set forth herein in detail.In the previous descriptions, numerous specific details are set forth,such as specific materials, structures, chemicals, processes, etc., inorder to provide a thorough understanding of the disclosure. However, itshould be recognized that the present disclosure can be practicedwithout resorting to the details specifically set forth. In otherinstances, well known processing structures have not been described indetail, in order not to unnecessarily obscure the present disclosure.

Only a few examples of the present disclosure are shown and describedherein. It is to be understood that the disclosure is capable of use invarious other combinations and environments and is capable of changes ormodifications within the scope of the inventive concepts as expressedherein.

EXAMPLES Example 1

A thermochromic coating was made by dispersing a thermochromic pigmentin the B Side of a two component polyurea based formulation. Theresulting cast thermochromic material was subjected to a heat source toraise the temperature. The thermochromic coating changed color frommagenta to clear passing through a temperature range of about 85 F to 95F (29° C. to 35° C.) demonstrating the desired effect.

Two percent by weight of the thermochromic pigment Matsui ChromicolorMagenta (F-O) Type 37 was dispersed by gently mixing into the Side Bformulation described below. The Side A and Side B components were thenmixed together by passing through a multi-plate hand delivered mixingelement and cast onto a release layer. The material was spread andallowed to gel and then cure at room temperature. The cast film achievedfull cure in about seven days. The free standing plastic film wasrepeatedly cycled from room temperature to about 110 F (43° C.). Atapproximately 90 F (32° C.), the magenta color faded leaving a nearclear colorless film. On cooling the magenta color was regenerated.

Wt % in Mix Side A Bayer Desmadur N-3300A Aliphatic Isocyanate 79.2Bayer Desmadur N-3400 Aliphatic Isocyanate 19.0 King Industries K-Kat6212 Zirconium Catalyst 2.0 Kaufmann Perenol E-8 Air Release Agent 1.0Side B Bayer Desmophen 550U Polyol 35.0 King K-Flex188 Polyol 35.0 KingK-Flex XM-308 Polyol 20.0 Dorf Katel Clearlink 1000 Diamine 7.9 MatsuiChromicolor Magenta (F-O) Type37 Pigment 2.0 Kaufmann Perenol E-8 AirRelease Agent 0.1

Example 2

A thermochromic coating was made by dispersing five weight percent of athermochromic pigment into the B Side of a two component polyureaformulation. The resulting cast thermochromic element was temperaturecycled and demonstrated the desired color change.

Five percent by weight of the thermo chromic pigment Hallcrest Black wasdispersed by gently mixing into the B Side formulation shown below. TheSide A and Side B components were then stirred together in a vessel fortwo minutes. The resulting liquid was spread with a foam paint brushonto a release surface and allowed to cure. The material was fully curedafter two days and subjected to heat cycle testing. The material changedfrom black to a very light gray on passing through a temperature rangeof about 85 F to 95 F. On cooling the black color was regenerated in thesample.

Wt % in Mix Side A Industrial Copolymers Incorez 701 Isocyanate 19.9Bayer N3600 Aliphatic Isocyanate 79.9 Kaufmann Perenol E-8 Air ReleaseAgent 0.2 Side B Reactamine 3000SP Diamine 24.5 Bayer NH 1420Polyaspartic Amine 69.9 Hallcrest Black Thermochromic Pigment 5.0Kaufmann Perenol E-8 Air Release Agent 0.2 Industrial Copolymers Incozol2 Moisture Scavenger 0.4

Example 3

A thermochromic coating was made by dispersing two weight percent of athermochromic pigment into the B Side of a two component polyurea basedformulation. The resulting spray applied thermochromic element wastemperature cycled and demonstrated the desired color change.

Two percent by weight of the Hallcrest Thermochromic Liquid CrystalBlack Pigment was dispersed by gently mixing into the B Side formulationshown below. The Side A and Side B components were mixed and sprayedusing a pneumatic piston driven cartridge spray system. The material wasdelivered to the static mixing element at IS psi piston pressure and 20psi aerosol pressure. The material was sprayed onto a release layer andallowed to cure. The material was fully cured in seven days andsubjected to thermal cycle testing. The coated material changed fromblack to a very light gray on passing through a temperature range ofabout 85 F to 95 F. On cooling the original black color was regenerated.

Wt % in Mix Side A Bayer Desmadur N-3300A Aliphatic Isocyanate 79.20Bayer Desmadur N-3400 Aliphatic Isocyanate 19.0 King Industries K-Kat6212 Zirconium Catalyst 2.0 Kaufmann Perenol E-8 Air Release Agent 1.0Side B Bayer Desmophen 550U Polyol 35.0 King K-Flex188 Polyol 35.0 KingK-Flex XM-308 Polyol 20.0 Dorf Katel Clearlink 1000 Diamine 7.9Hallcrest Thermochromic Liquid Crystal Black 2.0 Kaufmann Perenol E-8Air Release Agent 0.1

Example 4

A thermochromic coating was made by dispersing two weight percent of athermochromic pigment mixture into the B Side of a two componentpolyurea based formulation. The resulting spray applied thermochromicelement was temperature cycled and demonstrated the desired colorchange.

Two percent by weight of a thermochromic pigment mixture prepared from aseries of thermochromic pigments obtained from Kelly Chemical and shownbelow was dispersed by gently mixing into the B Side formulation shownbelow. The Side A and Side B components were mixed and sprayed using apneumatic piston driven cartridge spray system. The material wasdelivered to the static mixing element at 125 psi piston pressure and 50psi aerosol pressure. The material was sprayed onto a release layer andallowed to cure. The material was fully cured and subjected to thermalcycle testing. The coated material changed from brown to a very lightbeige on passing through a temperature range of about 80 F (27° C.) to90 F. On cooling the original brown color was regenerated.

Wt % in Mix Side A Bayer Desmadur N-3300A Aliphatic Isocyanate 79.2Bayer Desmadur N-3400 Aliphatic Isocyanate 19.0 King Industries K-Kat6212 Zirconium Catalyst 2.0 Kaufmann Perenol E-8 Air Release Agent 1.0Side B Bayer Desmophen 550U Polyol 34.0 King K-Flex188 Polyol 34.0 KingK-Flex XM-308 Polyol 19.0 Dort Katel Clearlink 1000 Diamine 7.15 KellyChemical Thermochromic Pigment Mixture* 5.75 Kaufmann Perenol E-8 AirRelease Agent 0.1 *The Kelly Thermochromic Pigment Mixture contains 17%Orange OT-31, 9% Magenta MT-31, 9% Black LT-31 and 65% Green GT-31.

Example 5

The material prepared as in Example 3) above was further coated with aUV protective layer comprising a nano-size TiO2 dispersion prepared bydispersing Sachtleben Hombitec RM 110 into a polyurea. The nano-sizeTiO2 dispersion was prepared according to the formulation below. Thepolyurea resin system labeled 750-2-2 is also shown below.

Item wt added in grams 750-2-2 Side B 13 Sachtleben Hombitec RM 110 0.65750-2-2 FL Side A 9.5 1) The HRM 110 was dispersed in 750-2-2 byaggressively stirring the pigment into the liquid. 2) 750-2-2 FL Side Awas then added followed by aggressive stirring. 3) The resultingdispersion was ready for coating. 750-2-2 Wt % in Mix Side A Bayer 3600Aliphatic Isocyanate 93.0 Huntsman Propylene Carbonate 7.0 Side B BayerVestamine 23.0 Bayer NH 1420 Polyaspartic Amine 55.0 Bayer NH1520Polyaspartic Amine 19.0 Kaufmann Perenol E-8 1.0 Industrial CopolymersIncozol 2 2.0

The nano-size TiO2 dispersion was coated on one side of the sprayedHallcrest Black prepared from Example 3) above at 10 mil coatingthickness. The resulting two layer system was allowed to cure for twodays. The resulting cured sample was thermally cycled to demonstrate thedesired color change from black to very light gray. Then the sample wasplaced in a QUV ultraviolet exposure device for one hour. After removalfrom the QUV unit the sample was again thermally cycled and the desiredcolor change from black to very light gray was again observed. Thisprocess was repeated four times with the same result demonstrating thenano-size TiO2 UV protective layer was preventing damage to thethermochromic pigments by absorbing the UV radiation.

Example 6

A two layer UV protected thermochromic film was prepared by coating anano-size TiO2 dispersion on a release Teflon block. Then athermochromic black layer was deposited on top of the already coated UVprotective layer. The sample was allowed to cure for two days, peeledfrom the release block and then subjected to thermal and QUV exposuretesting.

The UV protective layer was prepared according to the formulation belowand then coated at 20 mil thickness onto a Teflon release block.

Item wt added in grams 750-2-2 Side B 13 13 Sachtleben Hombitec RM 1100.65 750-2-2 FL Side A 9.5 1) The HRM 110 was dispersed in 750-2-2 byaggressively stirring the pigment into the liquid. 2) 750-2-2 FL Side Awas then added followed by aggressive stirring. 3) The resultingdispersion was ready for coating.

The thermo chromic layer was prepared according to the formulation belowand coated over the UV protective layer at a thickness of 30 mil. Thesystem was allowed to cure for two days at room temperature and then thefilm was peeled from the release block.

The two layer black thermo chromic film was thermally cycled and thedesired color change from black to very light gray was observed. Thefilm was then exposed to ultraviolet radiation in a QUV unit for onehour. After removal from the QUV unit the film was again thermallycycled and the desired color change was observed. This demonstrates theUV protective layer was absorbing the damaging ultraviolet radiation andprotecting the thermochromic pigment. This thermal/UV cycling wasrepeated four times with the same result.

Example 7

A three layer composite UV protected thermochromic structure wasprepared by coating a thermo chromic black layer onto a Teflon block.The sample was allowed to cure for two days, peeled from the releaseblock and then adhered to a white carrier sheet with a pressuresensitive adhesive to provide support for the thermochromic layer. Tothe opposite side of the thermochromic layer a UV protective film wasalso adhered to the thermochromic layer to provide protection from UVlight damage.

The UV protective layer is F007-005 obtained from UV Process Supply,Inc. The thermochromic layer was prepared as shown in Example 2.

The three layer black thermochromic composite was thermally cycled andthe desired color change from black to very light gray was observed. Thefilm was then exposed to ultraviolet radiation in a QUV unit for 24hours. After removal from the QUV unit the film was again thermallycycled and the desired color change was observed. The area not protectedby the UV protective layer showed significant damage from the UV lightexposure and did not demonstrate the desired full color change. Thisdemonstrates the UV protective layer was absorbing the damagingultraviolet radiation and protecting the thermo chromic pigment.

Example 8

A three layer composite UV protected thermochromic structure wasprepared by coating a thermochromic black layer onto a Teflon block. Thesample was allowed to cure for two days, peeled from the release blockand then adhered to a white carrier sheet with a pressure sensitiveadhesive to provide support for the thermochromic layer. To the oppositeside of the thermochromic layer a UV protective film was also adhered tothe thermo chromic layer to provide protection from UV light damage.

The UV protective layer is F007-005 obtained from UV Process Supply,Inc. to which a TiO2 additional UV protective nano-dispersion was coatedat 10 mil thickness. The thermochromic layer was prepared as shown inExample 2.

The three layer black thermochromic composite was thermally cycled andthe desired color change from black to very light gray was observed. Thefilm was then exposed to ultraviolet radiation in a QUV unit for 24hours. After removal from the QUV unit the film was again thermallycycled and the desired color change was observed. The area not protectedby the UV protective layer showed significant damage from the UV lightexposure and did not demonstrate the desired full color change. Thisdemonstrates the UV protective layer was absorbing the damagingultraviolet radiation and protecting the thermochromic pigment.

1. A thermochromic material, comprising: a substrate; and athermochromic coating arranged on the substrate, wherein thethermochromic coating comprises: a first layer containing: athermochromic compound; and a polyurea resin; and a second layercontaining: a resin; and a UV-blocking material, wherein: the secondlayer is arranged over the first layer, the UV-blocking materialcomprises particles having a diameter of from 0.005 μm to 0.4 μm, thesubstrate is one selected from the group consisting of: a structuralmaterial, a residential building material and an industrial buildingmaterial; and the thermochromic compound is at least one selected fromthe group consisting of leuco dyes, microencapsulated leuco dyes,spirolactones, spiropyrans, fluorans, cholesteryl nonanoates, andcyanobiphenyls.
 2. The thermochromic material of claim 1, wherein thethermochromic coating further comprises: a third layer containing areflective layer arranged under the first layer.
 3. The thermochromicmaterial of claim 1, wherein the second layer contains a polyurea resin.4. The thermochromic material of claim 1, wherein the first layerfurther comprises a UV-blocking material.
 5. The thermochromic materialof claim 1, wherein the concentration of particles in the second layeris from 0.1 wt % to 50.0 wt % of the total weight of the layer.
 6. Thethermochromic material of claim 1, wherein the polyurea is an aliphaticpolyurea.
 7. The thermochromic material of claim 1, wherein the polyurearesin further comprises a dendrimer or hyper-branched compoundcovalently bonded to the polyurea.
 8. The thermochromic material ofclaim 1, wherein the thermochromic compound has a thermochromictransition temperature of from 5° C. to 90° C.
 9. The thermochromicmaterial of claim 1, wherein the particles are comprised of a titaniumoxide.
 10. The thermochromic material of claim 1, wherein the particlesare comprised of an iron oxide.
 11. The thermochromic material of claim2, wherein the reflective layer arranged under the first layer comprisesa UV-blocking material.
 12. The thermochromic material of claim 11,wherein the UV-blocking material in the reflective layer comprisesparticles having a diameter of from 0.005 μm to 0.4 μm.
 13. Athermochromic coating comprising: a thermochromic compound; aUV-blocking material; and a resin comprised of at least one materialselected from the group consisting of: polyurethane, epoxy, acrylic,polyvinyl alcohol, polyvinyl chloride, fluoropolymers, siliconepolymers, and polyvinyl acetate, wherein the thermochromic compound andthe UV-blocking material are interspersed within the resin material. 14.A method for forming a thermochromic coating on a substrate comprisingthe step of: a) forming a first layer on the substrate, wherein thefirst layer comprises a thermochromic compound and a polyurea resin. 15.The method of claim 14, further comprising the step of: b) forming onthe first layer, a second layer having a UV-blocking material in asecond resin.
 16. The method of claim 15, wherein the second layercomprises a polyurea resin.
 17. The method of claim 15, wherein thesecond layer comprises a preformed UV blocking layer and is adhered tothe first layer with an adhesive.
 18. The method of claim 14, whereinthe polyurea is an aliphatic polyurea.
 19. The method of claim 15,further comprising the step of: c) before forming the first layer,forming a third layer on the substrate such that the reflective layer islocated between the substrate and the first layer.
 20. The method ofclaim 14, wherein the substrate is one selected from the groupconsisting of: a carrier film, a scrim structural sheet, a cellulosiccarrier sheet, a non-woven carrier sheet, ethylene-propylene dienerubber, chlorosulfonated polyethylene rubber, asphalt shingles, a roof,a pipeline, a delivery pipe, a chemical reactor, a building material, anindustrial structure and a residential structure.
 21. The method ofclaim 14, wherein the substrate contains a pattern or an image when thefirst layer is cycled through its transition temperature.
 22. The methodof claim 14, wherein the substrate contains infrared reflective pigmentsthat are revealed when the first layer is cycled through its transitiontemperature.
 23. The method of claim 14, wherein the first layer furthercomprises a UV-blocking material.
 24. The method of claim 15, whereinthe UV-blocking material comprises a plurality of particles having adiameter of from 0.01 μm to 2.5 μm.
 25. The method of claim 24, whereinthe concentration of particles in the second layer is from 0.1 wt % to50.0 wt % of the total weight of the second layer.
 26. The method ofclaim 14, wherein the resin further comprises a dendrimer orhyper-branched compound covalently bonded to the polyurea.
 27. Themethod of claim 14, wherein the thermochromic material has a transitiontemperature of from 5° C. to 90° C.
 28. The method of claim 24, whereinthe particles are comprised of a titanium oxide or an iron oxide. 29.The method of claim 14, wherein the thermochromic compound is at leastone selected from the group consisting of: liquid crystals,microencapsulated liquid crystals, leuco dyes, microencapsulated leucodyes, spirolactones, spiropyrans, fluorans, cholesteryl nonanoates,cyanobiphenyls and inorganic pigments.
 30. The method of claim 14,wherein the first layer is applied to the substrate by spraying amixture of the thermochromic compound and the polyurea resin at atemperature of from 5° C. to 50° C. and an aerosol pressure of from 1psi to 50 psi.
 31. The method of claim 14, wherein the first layer isapplied to the substrate by painting a mixture of the thermochromiccompound and the polyurea resin onto the substrate.
 32. The method ofclaim 14, wherein the first layer is applied to the substrate on a rollto roll coater using coating application methods selected from the groupcomprising: slot die coating, knife over roll coating, rod coating,extrusion coating and roll coating.
 33. The method of claim 19, furthercomprising a step: d) forming a fourth layer on the substrate, whereinthe fourth layer comprises a thermochromic compound and a polyurearesin.